This disclosure concerns an invention relating generally to snowplows, and more specifically to wing plows (also known as patrol wings) for snowplows.
Snowplows such as those commonly used to plow snow from roadways, parking lots, and other areas often include a front blade (often referred to as a front moldboard or similar terms) and a side blade (often referred to as a wing plow, wing blade, patrol wing, or similar terms). The front and side blades are often provided on a removable plow frame provided at the front of the plowing vehicle, and which may be detached from the plowing vehicle during snow-free months to allow other uses for the vehicle.
Regarding the side blades (which will generally be referred to herein as xe2x80x9cwing plowsxe2x80x9d), these generally have one of their sides hingedly mounted to the front of the plowing vehicle, and are driven by linear actuators such as hydraulic cylinders so that a wing plow may be folded up alongside (and somewhat parallel to) the plowing vehicle when not in use, and folded down to protrude along one side of the vehicle to travel along the ground when in use. Plowing with a wing plow takes practice and skill since it protrudes outwardly from the plowing vehicle by a significant distance, and the end of the wing plow can collide with objects in and alongside the road, e.g., mailboxes or vehicles in another traffic lane, if it is not withdrawn (folded to the vehicle) at the appropriate time. Difficulties in using wing plows are compounded because plowing generally occurs in conditions of low visibility (generally early in the morning during or shortly after a snowstorm), and at high speed owing to the need to rapidly enhance road safety for other motorists. The situation can be better appreciated if the reader contemplates the difficulties involved in driving a large vehicle in the dark during a snowstorm, while simultaneously listening to a radio dispatcher, steering the vehicle to appropriately orient the front moldboard, and actuating controls to adjust the positions of the wing plow and front moldboard so as to attain the desired snow removal and to avoid striking objects in and around the roadway.
These difficulties are compounded by the limited versatility of most wing plow mounts and actuation arrangements. Wing plows generally fold outwardly and downwardly from the plowing vehicle, i.e., they lift as they are folded inwardly toward a vehicle and drop when being folded outwardly. Thus, if a plow operator needs to partially fold a wing plow inwardly to avoid striking an object alongside the roadway, the wing plow may lift to such a degree that it no longer contacts the plowing surface. As a result, multiple passes with the plowing vehicle may be required to adequately remove snow from some areas. Additionally, it is generally impossible or very difficult for an operator to adjust the height of a wing plow to clear a raised area, e.g., above a curb, and when this is done the effective length (reach) of the wing plow tends to be greatly decreased.
Wing plows are also subject to greater durability and maintenance concerns than front moldboards. Like front moldboards, wing plows experience significant wear and shock as they scrape along an irregular roadway surface, and as they experience loading from snow, ice, and impact with objects in and alongside the roadway. However, since wing plows have their primary connection to the plowing vehicle at their sides, rather than at their centers (as with front moldboards), this connection is subject to significant stress owing to the moment forces generated during plowing. The connection can be reinforced, and hydraulic cylinders and/or other supports are often provided between the plowing vehicle and the outer end of the wing plow (the protruding end spaced away from the plowing vehicle) to bear a portion of the load experienced by the wing plow. While these measures strengthen the support for the wing plow, they can lead to greater maintenance burdens in the long run. When the wing plow""s primary connection to the plowing vehicle (at the side of the moldboard) is reinforced, this often tends to add such bulk to the wing plow mounting arrangement that access to the plowing vehicle""s hood is severely obstructed. This causes difficulties because the vehicle""s hood needs to be lifted quite often during the plowing season for maintenance of the vehicle""s engine, the plowing controls and hydraulics, etc., and if the plow frame and/or other wing plow mounting structure requires removal every time the vehicle hood is to be accessed, this can diminish the plowing vehicle""s available operating time. Access to the hood and/or other components of the plowing vehicle can be further obstructed when supports are added between the plowing vehicle and the outer end of the wing plow, and such supports, being subject to significant stress and wear, require additional maintenance. This is particularly true if such supports include hydraulics or similar xe2x80x9ccontrollablexe2x80x9d components which are relatively complex and which are more susceptible to shock damage, and which also enhance the operational complexity of the wing plow owing to the plowing vehicle operator""s need to actuate these components, along with other components of the plow, during plowing operations. Such supports also define additional connections that must be removed if the wing plow if to be removed from the plowing vehicle for maintenance or other reasons.
As a result, there is a need for arrangements whereby a wing plow""s height and effective length may be adjusted by a plowing vehicle operator as desired, with such arrangements preferably being easily controllable to reduce operational complexity for the plowing vehicle operator, and also preferably being relatively structurally simple for ease of maintenance and control.
The invention, which is defined by the claims set forth at the end of this document, is directed to a wing plow assembly which at least partially alleviates the aforementioned problems. A basic understanding of some of the preferred features of the invention can be attained from a review of the following brief summary of the invention, with more details being provided elsewhere in this document.
In a preferred version of the wing plow assembly, a lifting subassembly is provided to allow vertical lifting of the entire length of a wing plow, thereby allowing the wing plow to be lifted above roadway objects, raised for plowing of curbs, etc. Initially, the wing plow assembly includes a base member for mounting to a plowing vehicle (or to structures connected to a plowing vehicle, such as on a plow frame for a front moldboard). Upper and lower height adjustment arms each have a base end pivotally anchored to the base member, and an opposing plow end pivotally linked to a plow positioning leg. The base member, height adjustment arms, and plow positioning leg form a parallelogram linkage wherein the plow positioning leg may vertically swing on the height adjustment arms about the base member. A wing plow having a length extending between a inner end and a outer end has its inner end affixed to the plow positioning leg so that the wing plow may also vertically swing about the base member. A wing lift linear actuator (e.g., a hydraulic cylinder) is provided in the parallelogram linkage such that actuation of the wing lift linear actuator raises and lowers the plow positioning leg with respect to the base member (and plowing vehicle), and thus the wing plow is also raised and lowered with respect to the base member (and plowing vehicle).
A folding subassembly is also provided to allow folding of the wing plow with respect to the plowing vehicle. The wing plow inner end is preferably affixed to the plow positioning leg so that it may at least swing horizontally thereon, thereby allowing the wing plow outer end to be swung toward or away from the plowing vehicle. This is preferably done by pivotally mounting the wing plow inner end to the plow positioning leg, as by affixing the wing plow inner end to a wing plow anchor which is horizontally rotatable about a wing positioning bar on the plow positioning leg. A wing fold linear actuator then extends from the outer end of the wing plow to affix to structure associated with the plow positioning leg (such as the wing plow anchor), and the wing fold linear actuator is extendible and contractible to horizontally swing the wing plow about the plow positioning leg (and thus fold the wing plow with respect to the plowing vehicle). To allow the wing plow to fold upwardly with respect to the plowing vehicle as well as inwardly, the wing plow inner end may also be pivotally affixed to the wing plow anchor to allow it to vertically swing thereon when the wing fold linear actuator is actuated. It is additionally possible to allow the wing plow to xe2x80x9cfloat,xe2x80x9d i.e., to adapt its height to irregularities in the plowing surface, by allowing the aforementioned wing plow anchor to slide on the wing positioning bar as well as rotate about it.
Further advantages, features, and objects of the invention will be apparent from the following detailed description of the invention in conjunction with the associated drawings.